v8/test/js-perf-test/SwitchStatements/run.js
Mihir Shah 9711289d06 A jump-table implementation for constant case switch statements
The change is made since for switch statements with lots of cases,
where each case is a constant integer, the emitted bytecode is still
a series of jumps, when we can instead use a jump table.

If there are 6 or more cases (similar to GCC) of Smi literals, and
if the max Smi case minus the min Smi case is not more than 3 times
the number of cases, we use a jump table up front to handle Smi's,
and then use traditional if-else logic for the rest of the cases.

We then use the jump table in interpreter/bytecode-jump-table to
do the optimization.

This tries to go off issue 9738 in v8's issue tracker. It is not
exactly the same, since that recommends doing the work at JIT-time,
but has similar ideas. It also partially goes off issue 10764.

Bug: v8:9738
Change-Id: Ic805682ee3abf9ce464bb733b427fa0c83a6e10c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2904926
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75323}
2021-06-23 09:26:23 +00:00

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JavaScript

// Copyright 2017 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
load('../base.js');
load('switch_statement.js');
var success = true;
function PrintResult(name, result) {
print(name + '-SwitchStatement(Score): ' + result);
}
function PrintError(name, error) {
PrintResult(name, error);
success = false;
}
BenchmarkSuite.config.doWarmup = undefined;
BenchmarkSuite.config.doDeterministic = undefined;
BenchmarkSuite.RunSuites({ NotifyResult: PrintResult,
NotifyError: PrintError });